DOI: 10.1038/ngeo2592
论文题名: Internal deformation of the subducted Nazca slab inferred from seismic anisotropy
作者: Eakin C.M. ; Long M.D. ; Scire A. ; Beck S.L. ; Wagner L.S. ; Zandt G. ; Tavera H.
刊名: Nature Geoscience
ISSN: 17520894
出版年: 2016
卷: 9, 期: 1 起始页码: 56
结束页码: 59
语种: 英语
Scopus关键词: deformation
; mid-ocean ridge
; numerical model
; oceanic lithosphere
; olivine
; orientation
; seismic anisotropy
; seismic wave
; slab
; strike (geology)
; subduction zone
; wave propagation
; Ica
; Nazca
; Peru
英文摘要: Within oceanic lithosphere a fossilized fabric is often preserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of olivine crystals, such as within fossil fabrics, can generate anisotropy that is sensed by passing seismic waves. Seismic anisotropy is therefore a useful tool for investigating the dynamics of subduction zones, but it has so far proved difficult to observe the anisotropic properties of the subducted slab itself. Here we analyse seismic anisotropy in the subducted Nazca slab beneath Peru and find that the fast direction of seismic wave propagation aligns with the contours of the slab. We use numerical modelling to simulate the olivine fabric created at the mid-ocean ridge, but find it is inconsistent with our observations of seismic anisotropy in the subducted Nazca slab. Instead we find that an orientation of the olivine crystal fast axes aligned parallel to the strike of the slab provides the best fit, consistent with along-strike extension induced by flattening of the slab during subduction (A. Kumar et al., manuscript in preparation). We conclude that the fossil fabric has been overprinted during subduction and that the Nazca slab must therefore be sufficiently weak to undergo internal deformation. © 2015 Macmillan Publishers Limited. All rights reserved. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/106101
Appears in Collections: 气候减缓与适应 科学计划与规划
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作者单位: Department of Geology and Geophysics, Yale University, New Haven, CT, United States; University of Southampton, National Oceanography Centre, Southampton, United Kingdom; Department of Geosciences, University of Arizona, Tucson, AZ, United States; Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC, United States; Instituto Geofísico Del Perú, Lima, Peru
Recommended Citation:
Eakin C.M.,Long M.D.,Scire A.,et al. Internal deformation of the subducted Nazca slab inferred from seismic anisotropy[J]. Nature Geoscience,2016-01-01,9(1)